Earlier springs and later autumns: climate change sends nature awry

Spring is arriving earlier each year as a result of climate change, the first "conclusive proof" that global warming is altering the timing of the seasons, scientists announced yesterday.

In what is believed to be the world's largest study of seasonal events, such as the flowering of plants, autumnal leaf fall and insect behaviour, scientists found that spring now arrives six to eight days earlier across Europe than in the early 1970s. Warmer temperatures have also delayed autumn, by an average of three days in the past 30 years, the scientists report.

Countries that have experienced the greatest warming saw the earliest springs, according to the study in the journal Global Change Biology. In Spain, where early spring temperatures have risen by up to 1C a decade, spring now arrives two weeks earlier. Britain is warming at a slower rate, with temperatures creeping up 1C in the past three decades.

"Not only do we clearly demonstrate change in the timing of seasons, but that change is much stronger in countries that have experienced more warming," said Tim Sparks, an environmental scientist on the study at the Centre for Ecology and Hydrology at Monks Wood near Huntingdon. Dr Sparks said the shifting seasons were already disrupting sensitive ecosystems by knocking natural processes such as pollination out of kilter.

"One of the biggest problems is that species don't adapt to warming at the same rate. So if you have a bird that feeds on an insect that relies on a certain plant for food, and any one of those responds to warming differently to the others, the whole system can break down," he said.

Scientists from 17 countries took part in the study and analysed 125,000 records and observations in Europe compiled between 1971 and 2000. The records, which covered 542 plant species and 19 animals, showed that 80% of all leafing, flowering and fruiting was now happening earlier in the year.

Annette Menzel, a co-author on the study, said: "Unlike some studies that record individual species, this is the first comprehensive examination of all available data at a continental scale, using around 550 plant species, and the timing change is clear, very clear." The study has concerned scientists because it reveals the impact on nature of fairly modest temperature rises. Projections by the Intergovernmental Panel on Climate Change suggest that warming will increase more dramatically towards the end of the century unless serious efforts to reduce greenhouse gas emissions are brought in.

In Britain, sensitive and already threatened species such as the Scotch argus and mountain ringlet butterflies are most likely to suffer as temperatures continue to rise. Migratory birds that winter in Africa but return to Britain to breed are faring badly because they have not adapted to the earlier springs. "It's as if they're turning up late for a meal, in the middle of the main course, when the starter has gone," said Dr Sparks.

A warmer Britain is likely to see rarer species die off as already common species expand their territories. The losses are likely to be countered partly by the arrival of birds, moths and other insects from mainland Europe. "It has the potential to be very depressing. We wanted to identify and present these results to convince people that change is already happening and we need to act now to minimise damage in the future," said Dr Sparks.